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Green Tea
© Steven Foster
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Common names:
EGCG, Epigallocatechin GallateBotanical names:
Camellia sinensisParts Used & Where Grown
All teas (green, black, and oolong) are derived from the same plant, Camellia sinensis. The difference is in how the plucked leaves are prepared. Green tea, unlike black and oolong tea, is not fermented, so the active constituents remain unaltered in the herb. The leaves of the tea plant are used both as a social and a medicinal beverage.
What Are "Star" Ratings?
Reliable and relatively consistent scientific data showing a substantial health benefit.
Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
This supplement has been used in connection with the following health conditions:
| Used for | Amount | Why |
|---|---|---|
Abnormal Pap Smear | Twice weekly, apply a cream with 15% polyphenols to the cervix and/or take a 200 mg EGCG supplement daily | A preliminary study found that cervical dysplasia improved following treatment with epigallocatechin-3-gallate, a green tea flavonoid, for 8 to 12 weeks.
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| Used for | Amount | Why |
|---|---|---|
Colon Cancer | Drink a few cups per day | The polyphenols in green tea leaves may help protect against colon cancer.
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| Used for | Amount | Why |
|---|---|---|
High Cholesterol | 3 cups daily | Green tea has been shown to lower total cholesterol levels and improve people’s cholesterol profile. |
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| Used for | Amount | Why |
|---|---|---|
Leukoplakia | 3 grams daily of a combination of whole green tea, green tea polyphenols, and green tea pigments, along with painting the mixture on the lesions three times per day | A combination of whole green tea, green tea polyphenols, and green tea pigments painted on lesions may improve healing. |
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| Used for | Amount | Why |
|---|---|---|
Obesity | An extract supplying 270 mg of EGCG and 150 mg of caffeine per day | Green tea extract rich in polyphenols may support a weight-loss program by increasing energy expenditure or by inhibiting fat digestion. |
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| Used for | Amount | Why |
|---|---|---|
Prostate Cancer | Several cups per day (enough to provide 600 mg of catechins daily) | Drinking green tea or taking green tea catechins may help prevent prostate cancer in men at high risk of developing the disease. |
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| Used for | Amount | Why |
|---|---|---|
Sunburn | Apply a formula containing 10% green tea polyphenols before sun exposure | Green tea contains polyphenols that have antioxidant and anti-inflammatory activity, and studies have suggested that these polyphenols can protect skin against ultraviolet rays. |
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| Used for | Amount | Why |
|---|---|---|
Breast Cancer | Refer to label instructions | In one Japanese study, drinking green tea was associated with improvements in women just diagnosed with breast cancer.
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| Used for | Amount | Why |
|---|---|---|
Crohn’s Disease | Refer to label instructions | Green tea is a tannin-containing herb that may be helpful to decrease diarrhea during acute flare-ups and has been used for this purpose in traditional medicine. |
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| Used for | Amount | Why |
|---|---|---|
High Triglycerides | Refer to label instructions | Drinking green tea may have a positive effect on triglyceride levels. |
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| Used for | Amount | Why |
|---|---|---|
Hives | Refer to label instructions | Two components of green tea, the polyphenols epigallocatechin (EGC) and epicatechin gallate (ECG), are reported to have an antihistamine effect. |
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| Used for | Amount | Why |
|---|---|---|
Immune Function | Refer to label instructions | Green tea has stimulated production of immune cells and has shown anti-bacterial properties in some studies. |
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| Used for | Amount | Why |
|---|---|---|
Infection | Refer to label instructions | Green tea is an herb that directly attack microbes. |
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| Used for | Amount | Why |
|---|---|---|
Lung Cancer | Refer to label instructions | Numerous preliminary studies have shown an association between drinking green tea and a reduced risk of several types of cancer including lung cancer. |
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Traditional Use (May Not Be Supported by Scientific Studies)
According to Chinese legend, tea was discovered accidentally by an emperor 4,000 years ago. Since then, Traditional Chinese Medicine has recommended green tea for headaches, body aches and pains, digestion, depression, immune enhancement, detoxification, as an energizer, and to prolong life.
Also indexed as:
- botanicals,
- Camellia sinensis,
- green tea,
- herbal dietary supplements,
- herbal medicine,
- herbal remedies,
- herbal therapy,
- herbalism,
- plant Medicine
About this treatment
Common names:
EGCG, Epigallocatechin GallateBotanical names:
Camellia sinensisHow It Works
Green tea contains volatile oils, vitamins, minerals, and caffeine, but the primary constituents of interest are the polyphenols, particularly the catechin called epigallocatechin gallate (EGCG). The polyphenols are believed to be responsible for most of green tea’s roles in promoting good health.
Green tea has been shown to mildly lower total cholesterol levels and improve the cholesterol profile (decreasing LDL “bad” cholesterol and increasing HDL “good” cholesterol) in most, but not all, studies. Green tea may also promote cardiovascular health by making platelets in the blood less sticky.
Green tea has been shown to protect against the oxidation of cholesterol to a more toxic molecule (oxidized cholesterol). Consumption of green tea increases antioxidant activity in the blood. Oxidative damage to LDL can promote atherosclerosis. While population studies have suggested that consumption of green tea is associated with protection against atherosclerosis, the evidence is still preliminary.
Several animal and test tube studies have demonstrated an anticancer effect of polyphenols from green tea. In one of these studies, a polyphenol called catechin from green tea effectively inhibited metastasis (uncontrolled spread) of melanoma (skin cancer) cells. The polyphenols in green tea have also been associated with reduced risk of several types of cancer in humans. However, some human studies have found no association between green tea consumption and decreased cancer risk.
In a double-blind trial, people with leukoplakia (a pre-cancerous oral condition) took 3 grams orally per day of a mixture of whole green tea, green tea polyphenols, and green tea pigments orally, and also painted a mixture of the tea on their lesions three times daily for six months. As compared to the placebo group, those in the green tea group had significant decreases in the pre-cancerous condition.
Compounds in green tea, as well as black tea, may reduce the risk of dental caries. Human volunteers rinsing with an alcohol extract of oolong tea leaves before bed each night for four days had significantly less plaque formation, but similar amounts of plaque-causing bacteria, compared to those with no treatment.
Green tea polyphenols have been shown to stimulate the production of several immune system cells, and have topical antibacterial properties—even against the bacteria that cause dental plaque.
One study found that intake of 10 cups or more of green tea per day improved blood test results, indicating protection against liver damage. Further studies are needed to determine if taking green tea helps those with liver diseases.
Tea flavonoids given by capsule reduced fecal odor and favorably altered the gut bacteria in elderly Japanese with feeding tubes living in nursing homes. The study was repeated in bedridden elderly not on feeding tubes, and green tea was again shown to improve their gut bacteria. These studies raise the possibility of using green tea in other settings where gut bacteria are disturbed, such as after taking antibiotics. Further studies are needed to clarify the role of green tea in this respect, however.
High-tannin tea has been shown to reduce the need for blood removal from people with iron overload, or hemochromatosis, in an open study. The tea had to be taken with meals and without lemon or milk to be effective. Tea is believed to help in hemochromatosis by preventing iron absorption.
In a double-blind trial, men with precancerous changes in the prostate received a green tea extract providing 600 mg of catechins per day or a placebo for one year. After one year, prostate cancer had developed in 3.3% of the men receiving the green tea extract and in 30% of those given the placebo, a statistically significant difference. These results suggest that drinking green tea or taking green tea catechins may help prevent prostate cancer in men at high risk of developing the disease.
There are four case reports in which certain types of leukemia or lymphoma (low grade B-cell malignancies) improved after the patients began taking green tea extracts.
How to Use It
Much of the research documenting the health benefits of green tea is based on the amount of green tea typically consumed in Asian countries—about 3 cups (750 ml) per day (providing 240–320 mg of polyphenols). However, other research suggests as much as 10 cups (2,500 ml) per day is necessary to obtain noticeable benefits from green tea ingestion. To brew green tea, 1 teaspoon (5 grams) of green tea leaves are combined with 1 cup (250 ml) of boiling water and steeped for three minutes. Decaffeinated tea is recommended to reduce the side effects associated with caffeine, including anxiety and insomnia. Tablets and capsules containing standardized extracts of polyphenols, particularly EGCG, are available. Some provide up to 97% polyphenol content—which is equivalent to drinking 4 cups (1,000 ml) of tea. Many of these standardized products are decaffeinated.
Last Review: 05-11-2011
Copyright © 2011 Aisle7. All rights reserved. www.Aisle7.net
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.
© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.
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